Mapping the Volcano
5:00 am
Mon June 23, 2014

Researchers To Take 'CAT Scan' Of Plumbing Deep Inside Mount St. Helens' Gut

A group of Northwest scientists are sprinkling the landscape around Mount St. Helens with high-tech sensors as part of a new effort to map the volcano’s deep plumbing.

Scientists have a pretty good understanding of what’s happening right under the mountain, where a big chamber periodically fills up with magma before an eruption. Now they’re looking deeper — down dozens of miles — to the tubes and tunnels that feed that chamber.

They’ll be using a few different tools, including seismic monitors buried at 70 sites around the mountain. Those sensors don’t just measure earthquakes; they also can use seismic waves to sort of X-ray the earth.

"In a lot of ways, it's like a CAT scan in a hospital,” said John Vidale, Washington’s state seismologist, “where they spin you around and send waves through you in lots of different directions, and measure the differences between what they see on the different paths through you.”

Instead of making a picture of your insides, the seismometers will image the guts of the volcano. They’ll use both natural tremors and some man-made ones. In about a month, the scientists will detonate underground explosions and then measure how the shockwaves bounce around.

Another team will use different hardware to read changes in magnetic fields.

The whole effort is intended to tell us how different volcanoes might or might not be connected, and whether we can get earlier warnings of a potential eruption.